A communication method enabling high-speed/high-quality communications under existences of strong noises and obstacles is needed for building up smart grids etc. There has hitherto been disclosed a DS-SS (Direct Sequence Spectrum Spread) method as a communication method exhibiting an excellent anti-noise property and enabling multiple access, however, this method, though capable of improving a signal-to-noise ratio (SN ratio) by de-spreading and removing narrowband noises superposed on transmission signals on the way of performing communications outside a bandwidth, has such a problem that the SN ratio about broadband noises cannot be improved (Non-Patent documents 1, 2).
Disclosed further are a transmission apparatus of sequentially transforming input data into parallel data sequences, sequentially allocating the respective parallel data sequences to an N-number of channels (“N” is a natural number equal to or larger than “2”), sequentially transforming the individual parallel data sequences into predetermined orthogonal code sequences, e.g., Walsh function sequences, performing a spectrum spread modulation process by multiplying the orthogonal code sequences by predetermined spread codes respectively, generating an N-number of SS (Spread Spectrum) signals, adding delay values different in magnitude from each other to the respective SS signals, generating transmission multiplexed SS signals in a way that multiplexes the N-number of SS signals by a predetermined method, applying predetermined signal processing to the transmission multiplexed SS signals and thus transmitting these signals, and a reception apparatus of retaining partial spread codes obtained by dividing the spread code by a bit count “J” of the orthogonal code sequence, calculating a partial correlation value between the transmission multiplexed SS signal and each partial spread code, retaining an inverse matrix of an orthogonal code matrix with each orthogonal code sequence being used as a row element, calculating the orthogonal correlation value corresponding to each orthogonal code sequence by multiplying the inverse matrix by a column vector consisting of each partial correlation value, specifying the orthogonal code sequence with the orthogonal correlation value being maximized, making a maximum likelihood determination by outputting the parallel data sequences associated beforehand with the orthogonal code sequences as modulation parallel data sequences to the N-number of channels respectively, correcting a delay difference of the demodulation parallel data sequence of each channel on the basis of a delay quantity added to the SS signal of each channel in the transmission apparatus, sampling each demodulation parallel data sequence after correcting the delay difference on the basis of a regenerative symbol clock synchronizing with a repetitive cycle of the spread code of the transmission multiplexed SS signal, and obtaining series demodulation data sequences by parallel/series-transforming the sampling data of the individual channels (Patent document 4), however, such a problem exists that the orthogonal code sequence like the Walsh function is affected by the noises and gets easy to lose the orthogonality, and there increases a probability of occurrence of erroneous detection in the signals on which the noises are superposed.
Disclosed still further are an M-ary method aiming at fast transmission and a multi-valued M-ary method of representing data with a combination of a plurality of code sequences and with polarities, however, these methods have such problems that an improvement rate of the SN ratio of each method is equal to or smaller than by the DS-SS method, and, in the case of the multi-valued M-ary method, the individual M-ary signal is hard to be detected, and hence it is difficult to obtain a sufficient transmission speed by increasing a multiplicity (Non-Patent documents 1, 3, 4).
Disclosed yet further are a code sequence type transmission apparatus and reception apparatus (Patent documents 1, 2, 3) of generating a transmission signal by use of a multiplexed basic pulse train multiplexed by multiplying a spreading-applied code sequence of a cycle with data being mapped to shift time by an order pulse train consisting of spread code pulses of the cycle, and decoding the data by sequentially de-spreading the detected multiplied basic pulse train with the order pulse train, thus demultiplexing a low-speed code sequence and detecting a localization pulse thereof, however, there are such problems that the spread code sequence of this technology provides just the order, the data is mapped to only the spreading-applied code sequence, an information quantity per chip is therefore small, and a speed-up scheme, though attained by multiplexing the basic pulse train in order to compensate this defect, requires a long period of time for processing and gets circuits complicated, resulting in a rise in cost. Moreover, the SN ratio is improved by de-spreading the multiplexed basic pulse train of the cycle based on the order pulse train and localizing the signal undergoing de-spreading, however, there also exist such problems that de-spreading involves using the basic pulse train on the unit of cycle for the spreading-applied code sequence, a spreading rate cannot be therefore taken sufficiently with the result that the improvement rate of the SN ratio is restricted, and the speed-up scheme is restrained.
The existing technologies described above are different from the present invention in terms of configurations and methods, in which the present invention incorporates generating a multiplexing-spread chip sequence by performing subordinate multiplexing with a multiplicity being equal to or larger than “1” in an amplitude direction by multiplying chips of a spreading-purpose code sequence and chips of a coupling-purpose code sequence together, further multiplying chips of a localizing-purpose code sequence and linearly coupling the chips in a direction of a time base, generating a transform signal by multiplexing an OFDM (Orthogonal Frequency Division Multiplexing) signal with the multiplicity being equal to or larger than “1” that is generated by modulating orthogonal subcarriers with a single multiplexing-spread chip sequence or an aggregation of plural multiplexing-spread chip sequences by a frequency division method different per aggregation, or generating a transmission signal based on the transform signal generated by multiplexing a Wavelet OFDM signal with the multiplicity being equal to or larger than “1” that is generated by modulating an aggregation of Wavelets generated by a parameter setting method determined per aggregation with the aggregation of the multiplexing-spread chip sequences, acquiring and de-spreading the multiplexing-spread chip sequence from the transform signal transformed into a frequency domain on the reception side, and detecting the code sequence for determining each code sequence by combining the detection of the localization pulse in a multiplexing direction on the basis of the code sequence for the combination with the detection of the localization pulse in the direction of the time base on the basis of the localizing-purpose code sequence.
Moreover, the present invention is different from the prior arts in terms of enabling allowance of mapping the data to types of the respective code sequences including the spreading-purpose code sequence, the shift time or/and the polarities in the data transmission.